Create mvcc.py file

mvcc.py

+import storage
+import time
+
+class MVCC :
+    def getTimestampNow(self) :
+        return time.time()
+
+    def setTimestampNow(self, key, timestamp, storage = Storage) :
+        tempTimestamp = timestamp
+        storage.setdata[key]["timestamp"] = tempTimestamp
+
+    def read(self, key, storage = Storage) :
+        return storage.setdata[key]["value"]
+    
+    def write(self, key, value, storage = Storage) :
+        tempTimestamp = self.getTimestampNow()
+        if (storage.setdata[key]["timestamp"] > tempTimestamp) :
+            # rollback transaction and reject operation
+        else :
+            storage.setdata[key]["value"] = value
+            self.setTimestampNow(key, tempTimestamp, storage)
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